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What Is AS/NZS 1554.1?

AS/NZS 1554.1 is the Australian and New Zealand standard for structural steel welding. It covers arc welding of carbon and carbon-manganese steels in buildings, bridges, and other structures. The standard is organized into 6 parts by application, with Part 1 covering general structural welding.

AS/NZS 1554.1 — formally titled “Structural Steel Welding — Welding of Steel Structures” — is the joint Australian and New Zealand standard governing the welding of structural steel. Published jointly by Standards Australia and Standards New Zealand, it covers the qualification of welding procedures and welders, fabrication requirements, and inspection criteria for welded steel structures. The standard works alongside AS 4100 (Steel Structures) in Australia and NZS 3404 (Steel Structures Standard) in New Zealand.

The current edition is AS/NZS 1554.1:2014. The standard applies to the arc welding of carbon steels and carbon-manganese steels used in structures, buildings, bridges, and general fabrication. Related parts include AS/NZS 1554.2 (stud welding), AS/NZS 1554.4 (reinforcing steel), AS/NZS 1554.5 (high-strength quenched and tempered steels), and AS/NZS 1554.6 (stainless steel).

Welding Processes

AS/NZS 1554.1 covers MMAW (manual metal arc, equivalent to SMAW), GMAW, FCAW, SAW, and GTAW for structural steel. Process approval follows the same principle as D1.1: prequalified procedures (SP category) require documentation only, while non-prequalified procedures require qualification testing with destructive examination.

AS/NZS 1554.1 covers seven arc welding processes. The standard uses the ISO/Australian designation MMAW (Manual Metal Arc Welding) for the process that AWS D1.1 calls SMAW (Shielded Metal Arc Welding). The seven covered processes are:

MMAW (Manual Metal Arc Welding)

Equivalent to SMAW. The most commonly used process in Australian structural fabrication. Electrode classifications per AS/NZS 4855 (ISO 2560 equivalent). Hydrogen-controlled electrodes designated by hydrogen content suffix.

SAW (Submerged Arc Welding)

High-deposition process for shop welding of heavy plate, beams, and columns. Wire/flux combinations classified per AS/NZS ISO 14171. Commonly used for long continuous fillet and groove welds.

GMAW (Gas Metal Arc Welding)

Both spray transfer and short-circuit transfer modes are covered. Short-circuit GMAW is subject to additional restrictions under Section 4 of the standard. Wire classifications per AS/NZS ISO 14341.

GTAW (Gas Tungsten Arc Welding)

Used primarily for root passes, thin materials, and critical applications requiring precise heat control. Commonly used in combination with other processes for multi-pass welds.

FCAW (Flux-Cored Arc Welding)

Gas-shielded and self-shielded variants. Widely used in Australian fabrication shops and on-site welding. Wire classifications per AS/NZS ISO 17632.

ESW (Electroslag Welding)

Vertical-up single-pass process for thick plate butt joints. Limited to specific joint configurations and thickness ranges. Requires separate procedure qualification per Section 4.

EGW (Electrogas Welding)

Vertical-up process similar to ESW but using gas shielding instead of flux. Also limited to specific configurations and requiring separate qualification.

Weld Categories — GP and SP

AS/NZS 1554.1 classifies welds into two categories that determine inspection requirements and acceptance criteria. This is a fundamental structural difference from AWS D1.1, which uses static and cyclic connection categories instead.

GP (General Purpose): Welds in connections where the consequences of failure are lower. GP welds have less stringent acceptance criteria and may be accepted with visual inspection only in many cases. Typical applications include secondary steelwork, non-load-bearing connections, and connections in structures where redundancy is high.

SP (Structural Purpose): Welds in primary structural connections where failure could compromise structural integrity. SP welds require stricter inspection and acceptance criteria, including mandatory nondestructive examination for specified joint types. The design engineer specifies the weld category on the drawings based on the structural significance of the connection.

Weldability Groups and Carbon Equivalent

AS/NZS 1554.1 assigns base metals to weldability groups based on carbon equivalent (CE IIW). Group 1 steels (CE up to 0.40) require minimal preheat. Group 2 (CE 0.41 to 0.50) requires moderate preheat. Group 3 (CE above 0.50) requires controlled heat input and higher preheat. CE is calculated from the mill test report chemistry.

Instead of the lettered steel categories (A through G) used by D1.1 Table 5.11, AS/NZS 1554.1 organizes base metals into weldability groups numbered 1 through 12. The weldability group is determined by the carbon equivalent of the steel, calculated using the IIW formula: CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. Use our Carbon Equivalent Calculator to compute CE from mill test report data.

The weldability group directly influences the preheat requirement. Higher weldability group numbers correspond to higher carbon equivalents and therefore higher susceptibility to hydrogen-assisted cold cracking. The primary Australian structural steel standard, AS/NZS 3679.1, specifies grades like 300, 350, and 400 with yield strengths in MPa. These grades have controlled carbon equivalent ranges that determine their weldability group.

Preheat Determination

AS/NZS 1554.1 determines preheat from the combined thickness of the joint, the weldability group (based on carbon equivalent), and the hydrogen content of the welding consumable. Preheat temperatures are in degrees Celsius. The methodology is similar to D1.1 Table 5.11 but uses different grouping axes.

The preheat approach in AS/NZS 1554.1 differs fundamentally from both AWS D1.1 and CSA W59. Instead of discrete lookup tables, AS/NZS 1554.1 Clause 5.3.4 uses continuous curves that relate combined thickness, heat input, and weldability group to the required preheat temperature.

The procedure requires three steps. First, determine the weldability group from the steel's carbon equivalent. Second, calculate the combined thickness of the joint (sum of the thicknesses of the plates meeting at the joint). Third, use the appropriate figure — Figure 5.3.4(A) for the weldability index, Figure 5.3.4(B) for hydrogen-controlled processes, or Figure 5.3.4(C) for MMAW with non-hydrogen-controlled electrodes — to read the preheat temperature from the intersection of combined thickness and heat input.

This curve-based approach provides more granular control than a discrete table. It allows engineers to trade off between heat input and preheat: a higher heat input may permit a lower preheat temperature for the same weldability group and combined thickness, because the slower cooling rate achieves the same hydrogen diffusion objective.

How AS/NZS 1554 Compares to Other Standards

AS/NZS 1554 governs structural steel in Australia and New Zealand using metric units and local steel grade designations. D1.1 governs U.S. structural steel. Both provide prequalified WPS paths. Key differences: AS/NZS 1554 uses weldability groups based on carbon equivalent, references AS/NZS 2717 for filler metals, and organizes into 6 parts by application.

AS/NZS 1554 vs AWS D1.1

The standards serve the same purpose but differ in organization and approach. D1.1 uses discrete preheat tables with seven process categories (A through G), while AS/NZS 1554 uses continuous curves with weldability groups (1 through 12). D1.1 distinguishes between static and cyclic connections for acceptance criteria, while AS/NZS 1554 uses GP and SP weld categories. AS/NZS 1554 uses MMAW terminology instead of SMAW, references Australian material standards (AS/NZS 3679), and uses metric units exclusively. Both standards provide prequalified and qualified WPS paths. A WPS qualified under one standard cannot be used under the other without re-qualification.

AS/NZS 1554 vs CSA W59

CSA W59 uses discrete preheat tables (Table 5.3) with four process/hydrogen columns, while AS/NZS 1554 uses continuous curves. Both reference IIW-formula carbon equivalent, but organize the resulting steel classifications differently. CSA W59 requires W47.1 company certification, while AS/NZS 1554 does not have an equivalent company certification requirement (AS/NZS ISO 3834 quality management applies separately).

AS/NZS 1554 vs ASME Section IX

AS/NZS 1554 applies to structural steel construction, while ASME Section IX applies to pressure equipment. For Australian pressure vessel and piping work, AS/NZS 3992 (Pressure Equipment — Welding and Brazing Qualification) governs welding qualification rather than AS/NZS 1554. ASME IX uses a completely different base metal grouping system (P-numbers) and qualification framework.

Related Standards Guides

• ASME Section IX — Welding Qualification
• API 1104 — Pipeline Welding
• CSA W59 — Welded Steel Construction
• CSA W47.1 — Company Certification
• ASME IX P-Numbers Guide
• ASME IX F-Numbers Guide
• Pipeline Welding Requirements
• WPS — Welding Procedure Specification
• PQR — Procedure Qualification Record
• D1.1 Preheat Calculator
• CSA W59 Preheat Calculator
• AWS D1.2 — Aluminum
• AWS D1.3 — Sheet Steel
• AWS D1.4 — Reinforcing Steel
• AWS D1.6 — Stainless Steel
• AWS D1.8 — Seismic Supplement
• AWS D1.9 — Titanium
• AWS D1.5 — Bridge Welding Code